The present invention relates in general to compressors for air conditioning and refrigeration applications which use a compression element made of a metal disc with an integral scroll on one side and, more particularly, to methods of making such scroll compression elements to a near net shape using a single forming press stroke for each element.
An improved form of air conditioning and refrigeration compressor is being developed wherein rapid rotation of a disc having an integral scroll on one side forces refrigerant outward at high velocity. When the refrigerant's outward movement is impeded by the outer case of the compressor, the energy imparted to the refrigerant is transformed into pressure thus compressing the refrigerant. Such compressors are referred to as scroll compressors reflecting the refrigerant working disc/scroll element.
The scroll compressor elements are currently manufacture by casting aluminum and other appropriate metals with the resulting casting being machined to precise dimensions as required for a given compressor. Unfortunately, such castings have problems including porosity, excessive trim scrap and reduced material properties which make them less than ideal.
A process which is sometimes used as an improvement over casting is known as impact extrusion which is an extrusion process for producing tubular components by striking a metal blank, which has been placed in a die, with a punch moving at high velocity. Since scroll compressor elements are not tubular, they cannot be formed to near a net shape, i.e., the final shape of the a part to be manufactured, using such techniques. A blank could be formed using impact extrusion and then machined to final form. The resulting scroll compressor elements should have properties superior to the cast parts due to a lack of porosity and the orientation of the grain of the metal created by the impact extrusion. The grain orientation should also make such parts superior to fully machined parts.
While impact extrusion followed by machining is an improvement over completely machined scroll compressor elements and machined cast scroll compressor elements, there is a continuing need to further improve production techniques for scroll compressor elements.